The FormoSat-7 / COSMIC-2 constellation (simply known as FS-7/C-2) is an international collaboration between Taiwan (NSPO) and the United States (NOAA) that will use a constellation of 12 remote sensing microsatellites to collect atmospheric data for weather prediction and for ionosphere, climate and gravity research. NSPO/NARL (National Space Organization/National Applied Research Laboratories) is the designated representative for Taiwan and NOAA (National Oceanic and Atmospheric Administration) is the designated representative for the U.S. Note: NARL is also referred to as NARLabs.

FormoSat-7 / COSMIC-2 is a follow-on mission to the FormoSat-3 / COSMIC mission to meet the RO (Radio Occultation) data continuity requirements of the user community. NOAA and NSPO intend to provide a high-reliability next generation satellite system.

The overall objective of FS-7/C-2 is to advance the capabilities of regional and global weather prediction (including severe weather prediction). The goal is to collect a large amount of atmospheric and ionospheric data primarily for operational weather forecasting and space weather monitoring as well as meteorological, climate, ionospheric, and geodetic research. It is expected to be a much improved constellation system consisting of a new constellation of 12 satellites for an operation mission.

The primary mission payload will be a TriG (third generation) GNSS-RO receiver and will collect more soundings per receiver by adding European Galileo system and Russia's GLONASS (Global Navigation Satellite System) tracking capability, which will produce a significantly higher spatial and temporal density of profiles. These will be much more useful for weather prediction models and also for the severe weather forecasting including typhoons and hurricane, as well as for the related research in the fields of meteorology, ionosphere and climate. 1)2)3)4)5)6)7)8)9)10)11)12)13)14)15)16)17)18)

The constellation is planned to be comprised of 6 satellites at 72º inclination, and 6 satellites at 24º inclination, which will enhance observations in the equatorial region over what is currently being collected with FormoSat-3 / COSMIC. This constellation configuration was chosen because it provides the most uniform global coverage, as shown in Figure 1. Figure 1 shows the global sounding (data point) distribution versus the various orbital inclinations that were considered. 19)20)21)

This constellation will produce 8,000+ sounding profiles per day, compared to the approximate 2,000 soundings per day currently produced by FormoSat-3 / COSMIC due to the ability of FS-7/C-2 to track three navigation systems' signals (GPS, GLONASS, and Galileo) versus the ability of FormoSat-3 / COSMIC to track only one (GPS).

The project plan is to launch 2 rockets (Falcon-9) with 6 satellites on each rocket. They will be launched and then positioned into their final orbits (nominally 720 km altitude for the 72º inclination orbit and 520 km altitude for the 24º inclination orbit). 24)

The original FormoSat-3 / COSMIC mission had an operational concept of allowing for one data downlink per orbit. The plan for FS-7/C-2 is to allow for 2 data downlinks per orbit, which will considerably reduce the data latency. Consequently, FS-7/C-2 will require more satellite ground stations for receiving the data. As with FormoSat-3 / COSMIC, the data collected by FS-7/C-2 will be downlinked to the tracking station, then transmitted to the COSMIC processing center CDAAC (COSMIC Data Analysis and Archive Center) in Boulder, CO, as well as to the Taiwan processing center TACC (Taiwan Analysis Center for COSMIC) for processing.

The processed products will then be provided to the NOAA GTS (Global Transmission System) for distribution to the worldwide weather prediction centers. Command and control for the FS-7/C-2 constellation will continue to be provided by the NSPO SOCC (Satellite Operations Control Center). Payload operational configurations will continue to be managed by a joint effort between UCAR (University Corporation for Atmospheric Research) and JPL (Jet Propulsion Laboratory) with NOAA and NSPO concurrence for updates and changes.

• December 2015: President Ma Ying-jeou of Taiwan, together with Premier Mao Chi-kuo, the Minister of Science and Technology and other dignitaries, visited the National Space Organization (NSPO) recently, where they were invited to view progress on the assembly and testing of the FORMOSAT-5 AND FORMOSAT-7 satellites. During the visit, President Ma Ying-jeou and Premier Mao Chi-kuo observed a planned spacecraft solar array deployment test being performed by NSPO on one of the six FORMOSAT-7 spacecraft, with support from SSTL. 25)

- Three of the FORMOSAT-7 spacecraft have already completed their integration and test campaign in Taiwan, and all six spacecraft are scheduled to be ready for their FRR (Flight Readiness Review) in the first-half of 2016, ahead of their launch later in the year.

• May 1, 2015: SSTL has delivered the first spacecraft for the FormoSat-7/COSMIC-2 weather forecasting constellation to NSPO (National Space Organization) in Taiwan, where it has successfully passed a series of systems checks. 26)
The first shipment of satellites (FM1 and FM3) arrived at NSPO on March 24, 2015. Note: the FM1 is also referred to as the PFM (Proto-Flight Model). 27)28)

• March 2015: Amendment No.1 to the IA#1 through AIT/TECRO to update from 6-Satellite/1-Launch to 12-Satellite/2-Launch has been in work (Ref. 27).

On Sept. 6, 2012, NSPO awarded a contract to SSTL (Surrey Satellite Technology Ltd., UK) to built 12 minisatellites for the FormoSat-7/COSMIC-2 program. The spacecraft bus contract kick-off ceremony was held at NSPO (National Space Organization) and co-chaired by Dr. Guey-Shin Chang, Director General of NSPO, and Sir Martin Sweeting, Executive Chairman of SSTL. 29)30)

The first phase is to deploy 6 satellites, each carrying an advanced GNSS receiver, to low-inclination-angle orbits. The launch is targeted in 2016.

Under the contract, SSTL will design and manufacture satellites for the FormoSat-7 program at its facilities in Guildford, UK, with the payloads being produced by NSPO's partners in the USA. NSPO will be responsible for the integration of the majority of the spacecraft at its facilities in Taiwan. The spacecraft design phase is already underway and SSTL is tailoring a new 200 kg platform to the mission requirements.

Spacecraft design: The FS7/C-2 constellation will need to use the same mission control and mission operations ground system network as is being used for the FORMOSAT-3 system. The heritage baseline employed for the spacecraft is the SSTL-150 bus, which has been used on numerous previous missions. This configuration allows a more conventional design to be accommodated, without the need for extensive mass optimization and miniaturization. The avionics set provides a large degree of redundancy commensurate with mission lifetimes beyond 5 years. This bus is modified in some areas according to mission specific requirements. 31)

The propulsion system is based on heritage space components, and uses a monopropellant hydrazine system. Four thrusters are employed in order to permit spacecraft attitude control during propulsive maneuvers. Larger reaction wheels are employed to provide adequate control authority. Finally, star cameras are included to improve the attitude knowledge in support of the scientific payloads. One efficiency saving has been implemented by sharing capabilities cross the redundant OBCs (On-Board Computers) and redundant star camera processors, resulting in the need for just three computers. The resulting spacecraft avionics block diagram is shown in Figure 8.

RF communications: Use of COM DEV's S-band TT&C transponder, which was developed and certified under ESA's ARTES 3-4 program. The transponder combines the latest gallium nitride power amplifier technology with a flexible SDR (Software Defined Radio) system in a very light-weight, compact and efficient design, using commercially available components. The SDR is implemented on a field programmable gate array (FPGA), allowing the use of different modulation schemes and data rates to provide a flexible approach for different missions and mission phases. The transponder has previously been flown exactView-1 and is currently preparing to fly on a forthcoming M3MSat (Maritime Monitoring and Messaging Microsatellite) launch of Canada. 33)

- According to 'Spaceflight Now', the first STP-2 flight of SpaceX is scheduled for Q3 2017 (delayed from October 2016 and March 2017) with a cluster of military and scientific research satellites. The launch site is LC-39A at KSC (Kennedy Space center), FL. 35)

EELV-Grande launch option: This launch configuration provides a much more generous mass and volume allocation for the platform avionics. A more conventional design can be accommodated in this selection, without the need for extensive mass optimization and miniaturization.

• CP-9 , a joint CP-9/StangSat experiment, which is a collaboration between PolySat at Cal Poly and the Merritt Island High School, and is sponsored by the NASA LSP (Launch Services Program). CP-9 is a 2U CubeSat while StangSat is a 1U CubeSat.

Orbits:

• First launch: Six FormoSat-7/COSNMIC-2A satellites will be positioned in a low inclination orbit at a nominal altitude of ~520-550 km with an inclination of 24º. The parking orbit is 720 km. Through constellation deployment, they will be placed into 6 orbital planes with 60º separation.

• Second launch: Six FormoSat-7/COSMIC-2B satellites will be positioned in a high inclination orbit at a nominal altitude of ~720 km with an inclination of 72º. Through constellation deployment, they will be placed into 6 orbital planes with 30º separation.

As of October 2017, the U.S. National Oceanic and Atmospheric Administration (NOAA) and Taiwan's Ministry of Science and Technology agreed this month to scrap plans for a second set of next-generation GPS radio occultation weather satellites after determining the joint project faced an unwinnable battle to secure funding.

In a joint memorandum obtained by SpaceNews, the two agencies concluded that they would not pursue development of a second set of six COSMIC-2 (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites, known as COSMIC-2B, citing challenges to secure support in both countries.

FormoSat-7 / COSMIC-2 was originally planned to feature two sets of six satellites to collect GPS radio occultation data used in weather forecasting. An initial set of six satellites, known as COSMIC-2A, has been built and is scheduled for launch as part of the U.S. Air Force's STP (Space Test Program 2) mission, launching on a SpaceX Falcon Heavy in early 2018.

The COSMIC-2A satellites, operating in low-inclination orbits, were to be complemented by six satellites collectively known as COSMIC-2B that would operate in highly-inclined orbits. COSMIC-2B would be a replacement for the original Formosat-3/COSMIC satellites, launched into high-inclination orbits in 2006.

The satellites measure signals from GPS and other navigation satellites as they skim through the atmosphere, using them as a probe of temperature and humidity conditions that fed into weather forecast models. Studies have concluded that GPS radio occultation data is among the best sources of data for improving the accuracy of forecasts.

However, the memo, prepared by a joint Executive Steering Committee of U.S. and Taiwanese officials, found that both countries were finding problems financing the payloads, satellites and launch of the COSMIC-2B system.

"At the senior-level meetings on June 19-20, 2017, NOAA and NSPO both acknowledged the difficulty in finding a viable path forward in exercising the option for COSMIC-2B," the memo stated. NSPO is Taiwan's space agency, the National Space Organization.

NOAA, responsible for the COSMIC-2 payloads, did not receive any funding for the COSMIC-2B payloads in the fiscal year 2017 omnibus appropriations bill enacted in May. The agency's fiscal year 2018 request, released several weeks later, also requested no funding for COSMIC-2B payloads.

Uncertainty about funding for those payloads, in turn, created problems for NSPO, responsible for the satellites. "NSPO has had difficulty to secure the 2nd set of FORMOSAT-7 from the Ministry of Science and Technology (MOST) budget since 2014 because the funding of the second set of mission payloads remains uncertain," the memo stated.

Launch options for the COSMIC-2B mission were also an issue. NASA had proposed flying four the satellites as secondary payloads on the launch of the agency's Surface Water Ocean Tomography mission, scheduled for April 2021 on a SpaceX Falcon 9. However, NSPO "would face technical, schedule and resource challenges" in getting the satellites ready in time for that launch. The memo didn't state what plans, if any, existed for the other two COSMIC-2B satellites.

NSPO added that its ministry had given direction "not to pursue FORMOSAT-7 Launch #2 given new priorities," which were not stated in the memo.

That memo concluded that the Executive Steering Committee "decided not to exercise the option for COSMIC-2B/FormoSat-7." The joint program would proceed with the six COSMIC-2A satellites but "will not pursue additional FormoSat-7/COSMIC-2 satellites" beyond them. The memo was signed by NOAA officials Oct. 6 and by their Taiwanese counterparts on Oct. 16, 2017.

COSMIC-2 had become controversial in the U.S. because of perceptions by companies developing their own GPS radio occultation (RO) systems that the government was competing with them. NOAA, under pressure from Congress, started a pilot program in 2016 to purchase commercial GPS radio occultation data, awarding contracts to GeoOptics and Spire that concluded earlier this year.

In report language accompanying the 2017 omnibus appropriations bill, Congress indicated that it wanted to NOAA to consider commercial sources of that data alongside development of the COSMIC-2B satellites.

"Within 90 days of enactment of this Act, NOAA shall submit an analysis of options for acquiring polar RO data that includes a cost analysis of all alternatives and demonstrates that NOAA has thoroughly reviewed potential commercial RO sources," the act stated in the section discussing the lack of funding for COSMIC-2B.

"If the plan proposes moving forward with additional COSMIC-2 satellites," it continued, "the plan shall include the total cost to the U.S. government of developing, procuring, launching, and operating COSMIC-2 polar orbiting satellites, including how they would be launched and what Federal agency would incur that cost."

NOAA has not disclosed the outcome of analysis of data collected in the initial phase of the pilot program, where only Spire was able to provide GPS RO data. The memo, though, stated that NOAA didn't yet believe commercial data was ready for routine use. "While the commercial sector is not at present a viable source for [GPS radio occultation] data for operational use, NOAA will continue to evaluate it as a potential source for the future," the memo stated.

The Weather Research and Forecasting Innovation Act of 2017, signed into law in April, authorized continued development of a government-funded satellite system to collect GPS radio occultation data. The bill calls on NOAA to "complete and operationalize" the COSMIC-2 mission, placing satellites into both equatorial and polar orbits.

Table 6: Launch of the second set of the FormoSat-7/COSMIC-2 satellite is cancelled 37)

Initially in the project, the TGRS (Tri-band GNSS Receiver System) was referred to as TriG-RO [Tri-GNSS (GPS+ Galileo+GLONASS) Radio Occultation receiver].

TGRS (Tri-band GNSS Receiver System)

NASA/JPL (Jet Propulsion Laboratory) is developing a next-generation GNSS space science receiver, the TriG receiver. The receiver will upgrade the capabilities offered by the current state of the art BlackJack/IGOR GPS science receivers in order to meet NASA's decadal survey recommendations. This includes the ability to track not only GPS, but additional GNSS signals, including Galileo, CDMA GLONASS and Compass.

Most of the low level signal processing will be done inside multiple reconfigurable FPGAs, which can be updated post-launch to track new in-band GNSS signals as they become available. TriG will greatly increase the amount and quality of data by employing digital beamforming to direct multiple simultaneous high-gain beams at GNSS satellites.

With this new architecture and the availability of Galileo, GLONASS and Compass signals, many more occultations will be observed each day. The TriG receiver will have two processors, one for performing POD (Precise Orbit Determination), and the other dedicated to occultation and other science applications. The science processor will run Linux and can be programmed by scientists in a high-level scripting language, putting the scientist in the driver's seat when it comes to onboard processing of science data. 38)39)

The TriG receiver is a NASA funded instrument. The hardware development is at Moog Broad Reach (formerly Broad Reach Engineering), the software development and complete end-to-end testing is at JPL. 41)42)43)44)45)46)

• TriG design is based upon heritage derived from the BlackJack/IGOR receivers that flew on numerous missions with successful operation.

• NASA is scheduled to receive the "in place delivery" of the first fully tested EM (Engineering Model) by early summer of 2013.

• A second EM (with higher Navigation processor throughput capability) is also being built for NOAA in support of the COSMIC -2 program. The NOAA EM is upgraded to allow two additional RF down-converter cards and up to 16 antenna inputs to include surface reflection sensing capability and receiving DORIS signal.

For a full-up occultation receiver the spacecraft would also have to accommodate a fore and an aft occultation antenna (2.5 kg each) and a POD antenna (1 kg) with their attendant fields of view, and cables between the antennas and the receiver.

The TGRS receiver requires more capable antennas than those flown on missions such as COSMIC. To maximize the number of ionospheric and atmospheric profiles, the TGRS receiver will be capable of tracking legacy and new GPS signals such as L5, L2C and L1C; GLONASS CDMA and Galileo E1 and E5a. 48)

In 2013, Moog Broad Reach completed the TriG HW development in collaboration with NASA/JPL and has delivered the EM (Engineering Model) HW platform to Jet Propulsion Laboratory. 49)

3D printed antenna arrays:

In 2014, RedEye, a Stratasys Company and leading provider of 3D printing services, partnered with NASA/JPL to 3D print 30 antenna array supports for the FormoSat-7 /COSMIC-2 satellite mission. This is the first time, 3D printed parts will function externally in outer space. The antenna arrays will capture atmospheric and ionospheric data to help improve weather prediction models and advance meteorological research on Earth. 50)51)

A standard antenna array support design is traditionally machined out of astroquartz, an advanced composite material certified for outer space. Building custom antenna arrays out of astroquartz is time consuming and expensive because of overall manufacturing process costs (vacuum forming over a custom mold) and lack of adjustability (copper sheets are permanently glued between layers of astroquartz).

In order to keep the project on time and on budget, JPL needed an alternative method. They turned to RedEye to produce 3D printed parts that could handle the complex array designs and also be strong enough to withstand the demands of outer space. RedEye built the custom-designed parts using FDM (Fused Deposition Modeling) and durable ULTEM 9085 material, a thermoplastic that has similar strength to metals like aluminum but weighs much less.

Using FDM for a project like this has never been done before and it demonstrates how 3D printing is revolutionizing the manufacturing industry. While ULTEM 9085 has been well-vetted in the aerospace industry and is flammability rated by the FAA (Federal Aviation Administration), it has not previously been used or tested for an exterior application in space. Therefore, in addition to standard functional testing (i.e. antenna beam pattern, efficiency, and impedance match), FDM ULTEM 9085 and the parts had to go through further testing in order to meet NASA class B/B1 flight hardware requirements. Some of these tests included susceptibility to UV radiation, susceptibility to atomic oxygen, outgassing, thermal properties tests, vibration / acoustic loads standard to the launch rocket etc.

The ULTEM 9085's properties met all required qualification tests. To protect the antenna array supports against oxygen atoms and ultraviolet radiation, a layer of NASA's S13G protective paint was applied to the parts.

From March 2012 – April 2013, RedEye produced 30 antenna array structures for form, fit and function testing. As of 2014, RedEye was able to successfully enter the JPL Approved Supplier List and delivered 30 complete antennas for final testing and integration.

IVM (Ion Velocity Meter)

The USAF (U.S. Air Force) is partnering in FormoSat-7/COSMIC-2 and will provide two space weather payloads that will fly on the first six satellites: RF Beacon transmitters and IVM instruments.

In Feb. 2014, BATC (Ball Aerospace & Technologies Corp.) was awarded a contract from the Defense Weather System Directorate at the Space and Missile Systems Center in Los Angeles, Calif., for the production of the Ion Velocity Meter (IVM) under the U.S. Air Force Space Situational Awareness Environmental Monitoring program to fly aboard COSMIC-2.

The IVM instrument was originally designed by the University of Texas at Dallas (UTD). Ball Aerospace is under contract to build five replicas of the instrument under a firm fixed-priced contract. In addition to other operational space sensor programs, Ball Aerospace employs a disciplined technology transfer process to IVM based on prior collaboration with UTD on the National Polar-orbiting Operational Environmental Satellite System. 53)

All sensors are ram-facing. The IVM can measure the electric field perpendicular to the magnetic field and the ion motions parallel to the magnetic field through measurement of the ion drift velocity vector. Two sensors are part of the IVM package, the RPA (Retarding Potential Analyzer) and a DM (Drift Meter), which together provide data to determine the total ion concentration, the major ion composition, the ion temperature and the ion velocity in the spacecraft reference frame.

The SPLP is designed to measure absolute ion density, ion density fluctuations, and electron temperature. The SPLP has two independent sensor heads: an IT (Ion Trap) and a SP (Surface Probe). The Ion Trap is responsible for absolute ion density and density fluctuation measurements at sample rates up to 1 kHz for the identification of scintillating regions. The Surface Probe primarily measures electron temperature but also provides electron density, spacecraft potential and if necessary can perform the ion density fluctuation measurement. The power and data interface for IVM and SPLP is provided by the DCPU. It provides a single electronic interface between the spacecraft bus and the IVM sensors.

The RF Beacon includes the sensor electronics and antenna. The RF Beacon will transmit a coherent signal at frequencies in the UHF, L-band and S-bands. Ground receivers will intercept the signals and derive information on ionospheric scintillation.

• The ITT antenna design is a cylinder of 25 cm in diameter and 29.1 cm tall.

• The SRI RF beacon antenna unit will be set of 3 nested quadrafilar helix antennae, with outermost and largest element (UHF) to be ~ 14 cm in diameter and 23 cm high, and mounted on a circular base plate/ground plane approximately 25 cm in diameter. The complete antenna unit has a volume of 25 cm x 25 cm x 35 cm.

The information compiled and edited in this article was provided byHerbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (herb.kramer@gmx.net).